Definition
1, with specific shape, was thrown into the
water can meshes into the subsoil provides holding force, thus by anchor chain
of ship or other floating system left in the predetermined area of the
apparatus.
2, with a specific shape, was thrown into
the water to buried in the subsoil, providing grip and easy from out ,through
anchor chain or cable, to stable ship or other floats tethered in the waters of
special equipment.
Summary
Anchor is to have a specific shape, thrown
into the water can quickly gnaw into the subsoil providing grip strength,
through the top of anchor chain or cable, will leave the ship or other floating
system in the predetermined area of special equipment. Anchor is the main parts
make anchor force. The shape of anchor is special, usually made of forged steel
or cast steel. The anchor consists of anchor body and anchor bar, anchor consist
of anchor shackle, anchor shank, anchor crown, anchor arm, anchor fluke.
The number and weight of anchor are
determined according to the number of outfitting capacity, or according to the
ship's displacement, upper water is affected by wind area, resistance, anchoring
depth and the length of anchor chain. A ship with three main anchor (two bow anchor
and a spare anchor). Submarine anchor of superstructure use short shank anchor,
so as not to equip difficult. Anchor in the rated weight conditions to ensure
maximum grip strength and in any dropping conditions of various subsoil can
rapidly meshing, heaving up anchor and easy to emerge from the subsoil, close
to the broadside of hiding anchor when should be hawse pipe, anchor points, or
anchor frame fit well with.
Commonly the merchant vessel use stockless
anchor
Basic
requirements of anchor
Anchor is main device to tie the ship, its
performance directly affect ship’s reliably captive, so the performance put
forward very high requirements.
1 .grasping force
This is the most basic performance
requirements. Measurement of the performance of the ship's anchor holding
performance is usually referred to as the grasping force coefficient. Holding
force coefficient is equal to the quality of the anchor in the anchor in the
subsoil caught in the air force divided by the anchor. According to common
sense, the greater the quality of the anchor, the greater its grip strength;
but most of the anchor with the quality of the increase, the coefficient of its
grip force is a downward trend in the determination of the anchor should pay
attention to the characteristics of the.
2 .can adapt to a variety of different subsoil
quality
Generally, due to the vast area of
navigation, the bottom of the ship is very large, so the configuration of the
anchor type requirements can adapt to a variety of bottom.
3. solid structure
Ship in the process of anchoring and
mooring may bear a variety of complex load, so anchor structure should be
strong enough to ensure the safe use.
4, good stability, easy to merge
Ship in anchor mooring process, due to the
wind direction and the direction of the flow changes around the ship cast
anchor rotary, uneven ground the anchor force and cause anchor turn over and
was pulled out of the subsoil, so good stability for the anchor is very
important. Anchor bar with stability is better, but the collection inconvenience
anchor. In some cases, such as ship to load or a sudden increase in anchor may
still is from the subsoil in pull out, thus requiring anchor with re meshing
subsoil characteristics.
5 into soil short distance
Anchor is thrown into the water after, in
cable affects the fluke gradually meshes into the subsoil, from the beginning
to all mesh into the subsoil play maximum grip the distance shorter is better.
6 small pull force
The anchor, the anchor pull out from the
subsoil in force as small as possible, this will help reduce the burden of the
anchor machine.
7 good self-cleaning
The anchor in the anchor from the subsoil,
should not have a lot of dirt, otherwise it will increase the burden of the
anchor machine. At the same time anchor in the process of removing the water,
the soil should be basically clear clean.
8 convenient collection
General anchor used in the hawse pipe,
usually without rod rotating claw anchor is easier to be accepted into the
hawse pipe, anchor rod and fixed claw anchor that are the anchor frame.
Many types of anchor, according to its
structure and shape is divided into: stock anchor, stockless anchor, high
holding power anchor and special purpose single claw anchor, double fluke
anchor, grapnel anchor, bacteria anchor, floating anchor; divided by setting,
the location and use: bow anchor, stern anchor, spare anchor, shift anchors, position
anchor, back beach anchor and deep-sea anchor, mooring anchor etc.
Anchor structure
Like Hall anchor, composed of anchor shaft,
anchor body and shaft pin. Both the upper and the lower anchor hole, the upper
part of anchor hole connecting shackle, anchor hole at the lower part of body
is connected by a pin shaft .The anchor body is composed of two anchor fluke and
anchor crown .anchor crown in hole can make the anchor stem through that hole
has two and a half round groove, the pin shaft can rotate in the groove. To
prevent the anchor stem and pin to emerge from the crown, with two cross pin
pinned, and the cross pin and the anchor crown welded by welding. The prominent
part of crown on both sides called help catch make fluke easily buried in
subsoil.
Foundation
of anchor selection
Ships anchors and anchor chains according
to ships type and sailing waters, ship outfitting number in the column data to
select.
The number of ship outfitting, is a
parameter that reflects the hull can be wind, fluid flow force.
Cargo ships, bulk carriers, oil tankers,
ferries, trailing suction dredger is equipped with devices according to the
selected N. By the number of outfitting look-up table derived from a ship
should be the weight of the anchor in a matching number, each anchor and chain
level, length and diameter,
Usually more than ten thousand ton ships
are equipped with 3 main anchors, 2 bow anchor, 1 for preparation of anchor.
Ships sailing in narrow, curved and water potential complex channels are also
equipped with stern anchors to control the swing of stern when necessary.
Anchor
test
All anchor and main parts shall be made by
the authorized factory in accordance with the relevant regulations. The anchor
cast steel parts can be carried out by stretching test according to the same
furnace molten steel, the same specification, the same heat treatment procedure
and the total weight not exceeding 3T. At least 1 samples were drawn from each
batchA set of 3 impact specimens shall be taken for each batch of steel
castings used for high holding anchor, and the test shall be carried out at 0
degree. The average impact work is not less than 27J. The forged steel parts
shall be manufactured and tested in accordance with the relevant provisions.
Heat treatment should be carried out when a
single piece is more than 3T. The welding material approved welding anchor
assembly, according to the approved welding procedure by certified welders. All
finished anchors shall be inspected, weighed and tested in the absence of
paint.
Installation
requirements and test methods for anchors
Anchor and anchor chains, swivel, before
connecting the mounting ring should be carefully reproduces the ship inspection
product number, manufacturing factory product number and anchor quality. In
accordance with the requirements of the drawing, the specification and quantity
of the inspection can be shipped on board, and record the number of each.
Anchor of the visual inspection should be
carried out prior to painting, anchors and the part surface there should be no
cracks, pores, trachoma and other defects enough to affect strength of anchor,
to not affect the strength of surface defects allowed to repair welding repair.
Anchor shape and size of the margin of
error is 3%, but the sum of each ship bow anchor actual quality shall not be
less than standard anchor weight sum of; each new bow anchor when equipped with
quality limit of error is 7%; bolt bending in 1m length does not exceed 3mm;
the rotary angle of the flukes allowable deviation for -0.5o~+2o; when meet the
anchor quality deviation, size of each part of the allowed deviation is 4%, but
the maximum value shall not exceed 20mm.
The ship anchor can be divided into several
ways, such as mooring anchor, auxiliary ship operation anchor, emergency anchor
and so on.
1. mooring anchor
The ship for loading and unloading of
goods, such as wind and tide, waiting for a berth, and need moored at anchor.
Mooring anchor can hold. Loose the appropriate length of anchor chain, anchor
and anchor chain grasping in force to resist ship of water and wind and waves
on the ship's force. According to natural conditions of anchorage, can be
divided into single and double anchor mooring systems.
2 .auxiliary ship maneuvering anchor
In the narrow waterway navigation,
sometimes with anchor help turn around or steering, relying on berth or
emergency avoidance away with drag anchor to control the bow, control the hull
or brake reducing speed. The general maneuvering anchor chain is not long,
mainly from the block affection , do not request the anchor hold completely.
3 .emergency anchor
In the narrow channel traffic density
larger waters, sometimes for emergency avoidance can drag (double) anchor brake
to reduce the speed of ship, to avoid collision or collision loss is reduced.
If ship ran aground, along direction of anchor under refloating transport, hauling
chain to assist light. When ship encountered large waves, wind and air
stagnation can be anchored and loose chains of proper length to increase the
ship drifting resistance and is beneficial to control the bow, to assist the
ship resistance big waves.
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